The present invention relates to a displacement measuring method and a displacement measuring device for measuring displacement and deflection angle by using images.
Conventionally, a displacement and a deflection angle have been measured by projecting a predetermined pattern to an image sensor and by detecting a change.
In order to measure a displacement and a deflection angle with high precision, a high precision is required for the predetermined pattern, which is used as reference, and a pattern, which is a negative by elect lithography, has been used.
Further, in the measurement of deflection angle, the relationship between a projecting system and an image pickup system is rotated. When there is distortion in the image projecting system and the image pickup system, the distortion of the image is changed according to the rotation, and a low distortion has been required on the image (image pickup and image projection) device and an optical system to be used in the projecting system and the image pickup system.
For this reason, it has been costly to have a device, which enables to detect displacement and deflection angle with high precision.